I recently got Inarius’ Charger… and learned it. Didn’t think much of it.
Then I’m watching Hazel’s video about the current content, and she got the mount … except she also got an Achv!
I did a search for it, and it doesn’t even seem to exist. I tried re-logging, etc … I still don’t have an Achv.
The video is new, so it’s not like something she recorded from PTR that they removed.
What am I missing?
I’m thinking it’s an addon that she is using.
Rarity will pop a toast window that looks like an achievement but isn’t.
Maybe not Rarity, but something similar.
Because I also use Rarity, and it didn’t give me anything.
Or… maybe it’s just a setting on my end. 
From all I know there’s no fos connected to it, gotta be one of those “you obtained after X” fake achievement add-on things
There’s an addon that shows an achieve every time you collect a mount - it’s not an actual achievement
I can confirm you do not earn an achievement for obtaining the Inarius’ Charger mount in-game. Just looted this particular mount a few minutes ago and no achievement was rewarded.
What you likely saw was the AddOn “Rarity”. Rarity pops-up an achievement-type box whenever you collect a mount. However, Instead of saying “Achievement Earned” it will mention how many attempts it took you to earn that particular mount.
Additionally, If you uninstall this particular AddOn and then use it at a different point of time, Your mount attempt counter will reset back to zero.
I use the AddOn, Rarity and it showed a spash when I looted this particular mount. Took me (80) goblin kills to loot it according to the AddOn.
I think what you say was the addon Rarity being used by Hazel. It pops up a toast notification that looks like an achievement, but isn’t actually one.
Hope that helps~
That was so funny. She didn’t have the mount when she started making the video. But then when she went to capture some additional footage it went and dropped. Streamer luck.